function fixElement(element, message){
	alert(message);
	element.focus();
	return;
}

function validateHeartRate() {
	
	var passed=false;
	
	if ($get('heartrateage').value == "")
	{
	fixElement($get('heartrateage'), "Please enter your age");
	}
	else if (isNaN($get('heartrateage').value)){
	fixElement($get('heartrateage'), "Please enter a number in the age field");
	}
	else if ($get('heartrateintensity').selectedIndex==0)
	{
	fixElement($get('heartrateintensity'), "Please select an intensity level");
	}
		
	else {
		passed = true;
	}

	return passed;
}
	
function calculateHeartRate(){

validateHeartRate();

//reduce to two decimal places

	var age = parseFloat($get('heartrateage').value);
	var intensity = $get('heartrateintensity').selectedIndex;
	if (intensity == 1) {
	    intensity = .6;
	}
	else if (intensity == 2) {
		intensity = .7;
	}
	else if (intensity == 3){
		intensity = .8;
	}
	var target = parseFloat((220-age)*intensity);
	$get('heartratehr').value = Math.round(target);
	
}